Showing papers in "Bulletin of the Chemical Society of Japan in 1991"
TL;DR: In this article, the product selectivity of CO2 and CO was studied with a copper electrode in hydrogen carbonate solutions of various cations, i.e., Li+, Na+, K+, and Cs+ solutions.
Abstract: Electroreduction of CO2 and CO was studied with a copper electrode in hydrogencarbonate solutions of various cations. Product selectivity was greatly affected by cationic species as well as HCO3− concentration. H2 evolution prevailed over CO2 reduction in Li+ electrolyte, whereas CO2 reduction was favorable in Na+, K+, and Cs+ solutions. C2H4 formation became greater than CH4 with increase of the cation size, i.e. with sequence of Li+, Na+, K+, Cs+. The variation of the product selectivity caused by cationic species is rationalized by the difference of outer Helmholtz plane (OHP) potential. The OHP potential will vary with cationic species in accordance with the degree of specific adsorption. The concentration of H+ at the electrode will depend upon the OHP potential, since H+ is a charged species. This difference of pH at the electrode will lead to the variation of product selectivity.
322 citations
TL;DR: A method for polypeptide synthesis using S-alkyl thioester of a partially protected peptide segment has been developed and the DNA-binding domain of c-Myb protein was synthesized by this method to estimate its usefulness.
Abstract: A method for polypeptide synthesis using S-alkyl thioester of a partially protected peptide segment has been developed. The DNA-binding domain of c-Myb protein (142–193) was synthesized by this method to estimate its usefulness. The partially protected peptide segments, Boc–[Lys(Boc)143,144,160]–c-Myb protein(142–163)–SCH2CH2CONH2 and [Lys(Boc)171,182,192]–c-Myb protein(164–193)–NH2, were highly purified from peptides obtained by a solid-phase method. The thioester in the carboxyl component of the peptide segment was converted to the corresponding p-nitrophenyl ester in the presence of silver ions and p-nitrophenol and then the two segments were condensed. The coupling reaction proceeded almost completely yielding a highly-purified product after removal of Boc groups.
274 citations
TL;DR: In this article, photoexcited TiO2 particles were used to kill malignant HeLa cells with a 10-min UV irradiation period and showed little cytotoxicity up to 360 μg cm−3.
Abstract: Photo-irradiated TiO2 particles drive various chemical reactions due to their strong oxidation and reduction ability. This effect is applied in order to kill malignant HeLa cells with TiO2 particles. During 10-min UV irradiation periods, HeLa cells were completely killed in the presence of TiO2 (100 μg cm−3). However, without irradiation these particles showed little cytotoxicity up to 360 μg cm−3. It is concluded that the cells were killed by hydroxyl (OH·) and perhydroxyl (HO2·) radicals produced from water by the irradiated TiO2 particles, and also that the cells were directly oxidized by photogenerated holes in TiO2. The distribution of TiO2 powders in the cells was observed using a transmission electron microscope. The TiO2 powder existed not only on the cell membrane, but also in the cytoplasm. Thus, the cells were damaged by photoexcited TiO2 not only from the cell membrane, but also from the inside of cytoplasm. Finally, the application of this malignant cell photokilling effect to photodynamic th...
237 citations
TL;DR: In this article, the resonance frequencies of 13C, 29Si, and 1H nuclei in pure tetramethylsilane have been measured accurately by spinning the liquid sample at the magic angle, which are free from the effects of the bulk magnetic susceptibility and the solvent.
Abstract: The resonance frequencies of 13C, 29Si, and 1H nuclei in pure tetramethylsilane have been measured accurately by spinning the liquid sample at the magic angle, which are free from the effects of the bulk magnetic susceptibility and the solvent. Using the above resonance positions, the chemical shifts of several second shift-standard materials have been determined with much improved accuracy and precision.
211 citations
TL;DR: In this paper, the photocatalytic hydrogenation of CH3C≡CH and C3H6 in the presence of H2O was investigated, with a greater effect being observed on ZnO than on TiO2.
Abstract: Substantial differences in photocatalytic reactivity were observed on powdered TiO2 and ZnO, both Pt-loaded and unloaded, in the photocatalytic hydrogenation of CH3C≡CH and C3H6 in the presence of H2O. Similar reactivity was observed, however, in the photocatalytic oxidation of i-C4H8 and C3H6 by O2 on these same catalysts. Photoluminescence of TiO2 and ZnO in the presence and the absence of H2O and/or O2 indicate that H2O causes a downward band bending to increase the efficiency of recombination of photogenerated electrons and holes, with a greater effect being observed on ZnO than on TiO2. These results, together with the direct detection of reaction intermediates by ESR, are rationalized by differences in the yields of the photogenerated intermediates, i. e., H (formed from trapped electrons) and OH (formed from trapped holes). The steady state concentrations of these intermediates depend on the degree of the positively-charged adducts on the surfaces of these oxides. The addition of O2 causes an upwar...
156 citations
TL;DR: In the presence of a bis(1,3-diketonato)nickel(II) complex, various olefins are directly monooxygenated into the corresponding epoxides on treatment with atmospheric pressure of oxygen or air and aldehydes as discussed by the authors.
Abstract: In the presence of a bis(1,3-diketonato)nickel(II) complex, various olefins are directly monooxygenated into the corresponding epoxides on treatment with atmospheric pressure of oxygen or air and aldehydes. Especially, it is noted that bis[1,3-bis(p-methoxyphenyl)-1,3-propanedionato]nickel(II) behaves as an excellent catalyst in the present epoxidation.
154 citations
TL;DR: In this article, a theoretical equation of the reversible polarographic currentpotential curves for the ion transfer across the aqueous/organic interface facilitated by the neutral macrocyclic ligand present in the o-phase is derived without any limitation on the magnitude of distribution constant of the ligand.
Abstract: A theoretical equation of the reversible polarographic current-potential curves for the ion transfer across the aqueous/organic interface facilitated by the neutral macrocyclic ligand present in the o-phase is derived without any limitation on the magnitude of distribution constant of the ligand. In two limiting cases, which have been employed in common experimental practice, i.e., (A) the bulk concentration of cation, c*M, in the aqueous phase >> that of ligand, c*L, in the organic phase and (B) the reverse condition, c*M<
126 citations
TL;DR: In this article, the authors describe the 2CH3CH2CH2OH+H2O→CH3COOC2H5+2H2 and 3CH2COOH+H 2O+H1O→ CH3COCOH+2O2H 2H2, which were carried out over copper-based catalysts (Cu, Cu/SiO 2, Cu/ZrO 2 and Cu/MgO 2 ).
Abstract: The title reactions, 2CH3CH2OH→CH3COOC2H5+2H2 and CH3CH2OH+H2O→CH3COOH+2H2, were carried out over copper-based catalysts (Cu, Cu/SiO2, Cu/ZrO2, Cu/Al2O3, Cu/MgO, and Cu/ZnO). The selectivities to ethyl acetate and acetic acid markedly depended upon the supports used. Acetaldehyde was formed by the dehydrogenation of ethanol and transformed to either ethyl acetate or acetic acid through steps in which a nucleophilic addition of ethanol (or ethoxide ions) or water (or hydroxide ions) to acetaldehyde occurred. The rates of the transformation steps to ethyl acetate and acetic acid were appreciably affected by the kinds of supports used. The transformation steps proceeded slowly, compared with the dehydrogenation step.
118 citations
TL;DR: In this paper, the NMR spectra of pure nitromethane were measured with high resolution by spinning the liquid sample at the magic angle, using the precise resonance position of nitromethylene, and the chemical shifts of the solid second-standard materials such as ammonium salts and glycine have been measured.
Abstract: 15N NMR spectra of the shift standard compound, pure nitromethane, have been measured with high resolution by spinning the liquid sample at the magic angle. Using the precise resonance position of nitromethane, the chemical shifts of the solid second-standard materials such as ammonium salts and glycine have been measured with great precision.
111 citations
TL;DR: In this article, a variety of trialkylborane-induced reactions were examined for the preparation of α-carbonyl radicals: (1) addition of alkyl radical to methyl vinyl ketone, (2) reduction of α -halo ketone and (3) intramolecular radical addition to α,β-unsaturated carbonyl moiety.
Abstract: A variety of trialkylborane-induced reactions were examined for the preparation of the α-carbonyl radicals: (1) addition of alkyl radical to methyl vinyl ketone, (2) reduction of α-halo ketone, and (3) intramolecular radical addition to α,β-unsaturated carbonyl moiety. Trialkylborane reacted with α-carbonyl radicals to give boron enolates. The resulting boron enolates were efficiently trapped by carbonyl compounds to give β-hydroxy ketones in good yields.
105 citations
TL;DR: Methyl propargyl ethers, obtained from carbonyl compounds by successive treatment with an acetylide and MeI, were easily converted to the corresponding α,β-unsaturated ketone by regioselective hydration of acetylenic moiety followed by elimination of methanol under the catalytic action of Au(III) as discussed by the authors.
Abstract: Methyl propargyl ethers, obtained from carbonyl compounds by successive treatment with an acetylide and MeI, were easily converted to the corresponding α,β-unsaturated ketone by regioselective hydration of acetylenic moiety followed by elimination of methanol under the catalytic action of Au(III).
TL;DR: In this article, the levels of free radical species generated from six different systems (hypoxanthine-xanthine oxidase, iron(II)−hydrogen peroxide, iron (III)−t-butyl hydroperoxide, and catalase (CAT)−T-Butyl Hydroperoxide) were measured using ESR spin-trapping techniques.
Abstract: Using ESR spin-trapping techniques we measured the levels of free radical species generated from six different systems (hypoxanthine-xanthine oxidase, iron(II)–hydrogen peroxide, iron(III)–hydrogen peroxide, iron(II)–t-butyl hydroperoxide, iron(III)–t-butyl hydroperoxide, and catalase (CAT)–t-butyl hydroperoxide). Six types of radicals (O2−·,·OH, ·H, ·CH3, (CH3)3CO·, and (CH3)3COO·) were detected as spin adducts of spin traps 5,5-dimethylpyrroline 1-oxide (DMPO) or 3,5-dibromo-4-nitrosobenzene sulfonate (DBNBS). Quantitative analysis of the levels of generated radicals by means of an ESR instrument also presents important information regarding the reduction of peroxides [hydrogen peroxide (H2O2) or t-butyl hydroperoxide (ROOH)] by iron(II) or iron(III) as well as catalase. In addition, the scavenging potencies of different water-soluble antioxidants such as L-ascorbic, D-isoascorbic, gallic, sorbic, and protocatechuic acids were evaluated in terms of their ability to reduce the peaks of spin adducts.
TL;DR: Tris[1,3-bis(p-methoxyphenyl)-1, 3-propanedionato]iron(III) (Fe(dmp)3) was found to be an excellent catalyst for oxygenation of a number of olefinic compounds including styrene analogues and ole finics into the corresponding epoxides in good to quantitative yields with combined use of molecular oxygen and an aldehyde at room temperature.
Abstract: Tris[1,3-bis(p-methoxyphenyl)-1,3-propanedionato]iron(III) (Fe(dmp)3) was found to be an excellent catalyst for oxygenation of a number of olefinic compounds including styrene analogues and olefinic alcohols into the corresponding epoxides in good to quantitative yields with combined use of molecular oxygen and an aldehyde at room temperature.
TL;DR: In this paper, a series of polymethylene-linked heterobinuclear complexes of polypyridine ruthenium(II)/osmium (II) complex Ru(II)(bpy)2Mebpy-(CH2)n-mebpyOs(II),bpy2(bpy=2,2′-bipyridine and n =2, 3, 5, and 7), 1, was prepared.
Abstract: A novel series of polymethylene-linked heterobinuclear complexes of polypyridine ruthenium(II)/osmium(II) complex Ru(II)(bpy)2Mebpy–(CH2)n–MebpyOs(II)(bpy)2(bpy=2,2′-bipyridine and n=2, 3, 5, and 7), 1, was prepared. The photophysical behavior was examined in various solvents. The emission spectra of 1 (excitation wavelength: 455nm) showed a nearly complete quenching of RuII→π*(bpy) metal-to-ligand charge transfer (MLCT) emission and the enhancement of OsII→π*(bpy) MLCT emission. The luminescence lifetime measurements by a time-correlated single photon-counting method provided evidence that intramolecular energy transfer is a significant pathway for the observed emission quenching. The rate constants of the intramolecular energy transfer in ethanol are 5.3×108, 3.3×108, 1.3×108, and 1.0×108s−1 for 1(n=2, 3, 5, and 7), respectively. They were found to be proportional to the inverse sixth power on the center-to-center distance of the two complexes. The mechanism is discussed in terms of the Forster (a dipol...
TL;DR: In this article, an exhaustively reduced polypyrrole film was laid on an insulating glass plate and connected electrically to an ITO electrode at the marginal part, and the film absorbance to a monochromatic light beam was monitored with a photodiode array detector at 14 segments of the film.
Abstract: According to the propagation theory of a conductive zone for the electrochemical doping process of conducting polymer films, an oxidized conductive zone works as an electrode for oxidizing the reduced non-conductive region and is propagated throughout the film under charge transfer control. This theory was verified for polypyrrole films by tracing the temporal and spatial variations of conductive regions in a film. An exhaustively reduced polypyrrole film was laid on an insulating glass plate and connected electrically to an ITO electrode at the marginal part. The film absorbance to a monochromatic light beam was monitored with a photodiode array detector at 14 segments of the film. When the potential of the ITO electrode was stepped to an oxidation potential of the film, an electrochemically oxidized conductive zone was propagated through the film with a manifest phase boundary. The distance from the edge of the ITO electrode to the front of the conductive zone increased linearly with time. The logarithm...
TL;DR: The absorption and fluorescence spectra of 2-(2-aminophenyl)-, 2-(3-amino-polyethylene)-, and 2-(4-amphenyl)benzothiazoles (o-APBT, m-APB, and p-APBP, respectively) have been studied in different solvents and at various acid/base concentrations as mentioned in this paper.
Abstract: The absorption and fluorescence spectra of 2-(2-aminophenyl)-, 2-(3-aminophenyl)-, and 2-(4-aminophenyl)benzothiazoles (o-APBT, m-APBT, and p-APBT, respectively) have been studied in different solvents and at various acid/base concentrations. The ultraviolet and fluorescence spectra and the low pKa value for the monocation–neutral equilibrium have indicated the presence of an intramolecular hydrogen bond (IHB) in o-APBT in the S0 state. Excited state intra-molecular proton transfer (ESIPT) in o-APBT, gives rise to a non-fluorescent phototautomer. Large solvatochromic shifts in polar solvents have indicated the increase in the dipolemoment of m-APBT in S1 state. It has been observed that in protic solvents, m-APBT forms a complex with solvent molecule in the S1 state. The equilibrium constants for different prototropic equilibria of the molecules have been determined in both S0 and S1 states. The absorption and fluorescence spectra of the prototropic species have been explained and compared with those of 2...
TL;DR: In this article, the first stable 1 : 1 salt structure of the pyridine nucleus and halogen atom was assigned based on spectral and elemental analyses. But the stability depended on the nucleophilicity or basicity of the counter anions and electronic nature or position of the ring s. The scope of each method was examined in detail.
Abstract: Various stable N-fluoropyridinium salts with a non- or weakly nucleophilic counter anion such as TfO−, FSO3−, BF4−, SbF6−, ClO4−, CH3SO3− etc., or with an electron-donating or -withdrawing substituent(s) on the pyridine ring were synthesized and their properties investigated. N-Fluoropyridinium-2-sulfonates, N-fluoroquinolinium triflate, and highly hindered N-fluoro-2,6-di-t-butylpyridinium salts were also synthesized. They were synthesized by counter anion displacement reactions of unstable pyridine-F2 compounds, fluorination of salts of pyridines with protonic acids or silyl esters with F2, and/ or fluorination of Lewis acid complexes of pyridines. The scope of each method was examined in detail. Each of the N-fluoropyridinium salts was assigned as the first stable 1 : 1 salt structure of the pyridine nucleus and halogen atom on the basis of the spectral and elemental analyses. The stability depended on the nucleophilicity or basicity of the counter anions and electronic nature or position of the ring s...
TL;DR: The crystal structures of polymorph II of diisothiocyanatobis(2,2′-bipyridine)iron(II), [Fe(bpy)2(NCS)2], in the high- (298 K) and low-spin states (175, 110 K) were determined by an X-ray diffraction method.
Abstract: The crystal structures of polymorph II of diisothiocyanatobis(2,2′-bipyridine)iron(II), [Fe(bpy)2(NCS)2], in the high- (298 K) and low-spin states (175, 110 K) were determined by an X-ray diffraction method. The crystal is orthorhombic, space group Pcnb and Z=4 over the entire temperature range. At 298 K, a=13.2044 (6), b=16.4820 (7), c=10.1086 (7) A, U=2200.0 (2) A3, Dc=1.462 g cm−3 and at 110 K, a=12.9842 (9), b=16.1067 (12), c=9.8938 (8) A, U=2069.1 (3) A3, Dc=1.555 g cm−3. The structures were refined to R=0.047, 0.044, and 0.042 at 298, 175, and 110 K, respectively. The difference in the average Fe–N bond lengths between high- and low-spin states is 0.17 A. The pressure dependence of the absorption spectra was also measured up to 8.5 GPa using a diamond anvil cell. These results indicate that with increasing pressure the high-spin state at 1 atm starts to change to the low-spin state at 0.3 GPa and that its low-spin state reverts again to the high-spin state at around 3.3 GPa.
TL;DR: In this article, the Schiff base ligand was used to obtain the 13C NMR, absorption, and circular dichroism spectra, and conductivity measurements of Titanium(IV) complexes, [TiCl(Schiff base)]2O.
Abstract: Titanium(IV) complexes, [TiCl(Schiff base)]2O, with quadridentate Schiff base ligands derived from optically active 1,2-diamines and salicylaldehyde were prepared by treating TiCl4 with an equimolar amount of the Schiff base ligand in wet pyridine. The complexes were characterized by their 13C NMR, absorption, and circular dichroism spectra, and conductivity measurements. The complexes in dichloromethane take a μ-oxo dinuclear structure, and in methanol the complexes break up into a mononuclear species, [Ti(OMe)(MeOH)(Schiff base)]Cl. The complexes catalyze the asymmetric oxidation of methyl phenyl sulfide into the sulfoxide with organic hydroperoxides; the highest enantiomeric excess (ee) was ca. 60%. The kinetics conform to a rate law which is first order in the concentration of each sulfide, hydroperoxide, and complex catalyst.
TL;DR: In this article, the reaction of 1,1-dimethyl-1-silacyclobutane (1a) with dimethyl acetylenedicarboxylate (EDC) in the presence of Pd catalyst provides dimethyl 1, 1,dimethyl -1-sila-2-cyclohexene-2,3-dicaroxylate.
Abstract: Whereas the reaction of 1,1-dimethyl-1-silacyclobutane (1a) with dimethyl acetylenedicarboxylate in the presence of Pd catalyst provides dimethyl 1,1-dimethyl-1-sila-2-cyclohexene-2,3-dicarboxylate...
TL;DR: In this paper, a reaction mixture consisting of perfluoroalkylated silyl enol ethers and α-perfluoro-alkyl-ated ketone with coned HCl in THF gives a single product.
Abstract: Reaction of perfluoroalkyl iodides with silyl enol ethers mediated by Et3B in the presence of base such as 2,6-dimethylpyridine provides mixtures of perfluoroalkylated trialkylsilyl enol ethers and α-perfluoroalkylated ketones. The yield and distribution of the products heavily depend on the nature of base employed. Treatment of a reaction mixture consisting of perfluoroalkylated silyl enol ether and α-perfluoroalkylated ketone with coned HCl in THF gives α-perfluoroalkylated ketone as a single product. Reaction of ketene silyl acetals with perfluoroalkyl iodides in the absence of base affords α-perfluoroalkylated esters in excellent yields.
TL;DR: In this article, the solvent polarity parameters of supercritical carbon dioxide were determined as a function of the temperature and pressure within the ranges 318-353 K and 5.85-28.5 MPa.
Abstract: The solvent polarity parameters of supercritical carbon dioxide were determined as a function of the temperature and pressure within the ranges 318–353 K and 5.85–28.5 MPa. An infrared (IR) spectroscopic technique has been employed to determine the values of π* dipolarity/polarizability and the Lewis basicity parameter BMeOD by measuring the transitions in the IR absorption wavelength of functional groups (such as C=O and O–H···BA, where BA is a hydrogen-bond acceptor), in supercritical carbon dioxide. Ultraviolet/visible (UV/vis) spectroscopy was used to determine the value of the Kamlet-Taft’s solvatochromic acidity partameter, α. The BMeOD-value was enhanced with density, but was very small at the temperatures and pressures examined, almost the same as that for hexane. The α-value tended to be dependent on density at lower pressures, but was remarkably smaller compared with those for alcohols. The π*-value significantly increased with an increase in the density, becoming more negative at higher tempera...
TL;DR: In this article, a new halogenated C15 nonterpenoid with a novel carbon framework, named notoryne, has been isolated from the title alga and its structure was established on the basis of spectroscopic and chemical evidence.
Abstract: A new halogenated C15 nonterpenoid with a novel carbon framework, named notoryne, has been isolated from the title alga and its structure was established on the basis of spectroscopic and chemical evidence. In addition, the structure of a rearranged product, whose structure has long remained unsettled, of laurefucin derivative was also determined by spectral and chemical methods. Furthermore, the biogenesis of the halogenated C15 nonterpenoids from L. nipponica collected at warm current region in Hokkaido is also discussed.
TL;DR: In this article, three discrete binuclear gadolinium(III)-copper(II) complexes (CuGd(fsadien)NO3·5H2O (1), CuGd (hsapn) NO3·3H2Os (2), and Gd(pvm)3Cu(A)] (3)) have been synthesized; they use the notation H4fsaddien=N,N′-bis(3-carboxysalicylidene)diethylenetriamine, H4hs
Abstract: Three discrete binuclear gadolinium(III)–copper(II) complexes (CuGd(fsadien)NO3·5H2O (1), CuGd(hsapn)NO3·3H2O (2), and [Gd(pvm)3Cu(A)] (3)) have been synthesized; we use the notation H4fsadien=N,N′-bis(3-carboxysalicylidene)diethylenetriamine, H4hsapn=N,N′-bis(3-hydroxysalicylidene)-1,2-propanediamine, Hpvm=dipivaloylmethane (2,2,6,6-tetramethyl-3,5-heptanedione), and H2A=4-(6-methyl-8-oxo-2,5-diazanona-1,5,7-trienyl)imidazole. Magnetic susceptibility measurements (4.2–300 K) have revealed that the spin coupling between the Gd(III) and Cu(II) ions is ferromagnetic with coupling constants J=+2.3 cm−1 for (1), +5.7 cm−1 for (2), and +0.5cm −1 for (3), on the basis of the spin-Hamiltonian H=−2JSGd·SCu.
TL;DR: In this article, a catalyst system comprising [Pd2(dba)3]·CHCl3 and DPPF was proved to be efficient for the cyanation of aryl iodides and triflates with KCN.
Abstract: A catalyst system comprising [Pd2(dba)3]·CHCl3 and DPPF was proved to be efficient for the cyanation of aryl iodides and aryl triflates with KCN. The reactivities of aryl substrates decreased in the order ArI>ArOTf>ArBr.
TL;DR: In this paper, non-symmetric diarylethenes with an indole ring on one end and a thiophene, a benzo[b]thiophene or a pyrrole ring on the other end of the double bond were synthesized in an attempt to get thermally irreversible photochromic compounds having absorption bands at longer wavelengths.
Abstract: Non-symmetric diarylethenes with an indole ring on one end and a thiophene, a benzo[b]thiophene, or a pyrrole ring on the other end of the double bond were synthesized in an attempt to get thermally irreversible photochromic compounds having absorption bands at longer wavelengths 2-(1,2-Dimethyl-3-indolyl)-3-(2,4,5-trimethyl-3-thienyl)maleic anhydride(8a) underwent photoinduced cyclization/ring-opening reactions with relatively high quantum yields (cyclization quantum yield: 015; ring-opening quantum yield: 040), and the both isomers were thermally stable The closed-ring form had the absorption maximum at 595 nm with the edge extending to 760 nm Cyclization/ring-opening reactions of 8a and 2-(1,2-dimethyl-3-indolyl)-3-(2-methyl-3-benzo[b]thienyl)maleic anhydride (9a) were induced by Ar ion (488 nm) and He–Ne (633 nm) lasers
TL;DR: In this article, two kinds of N-salicylideneaniline derivatives, N-tetrachlorosalicylidsene-1-pyrenylamine (CL4SA) and CL4SPY, have been prepared and subjected to structural and optical studies in the crystalline state.
Abstract: Two kinds of N-salicylideneaniline derivatives, N-tetrachlorosalicylideneaniline (CL4SA) and N-tetrachlorosalicylidene-1-pyrenylamine (CL4SPY), have been prepared and subjected to structural and optical studies in the crystalline state. A thermochromic-type behavior of the former crystal has been observed as a shift of the absorption edge, while that of the latter crystal is much less pronounced. Fairly short O–H···N hydrogen bonds have been found in both compounds through crystallographic studies, which may be mainly due to a steric effect of chlorine substituents. The difference in the proton transfer behavior of CL4SA and CL4SPY should presumably be caused by an intermolecular charge-transfer interaction in the latter crystal.
TL;DR: In this article, the synthesis of α,β-unsaturated ketones by means of the palladium-catalyzed cross-coupling reaction between 9-alkyl-9-borabicyclo[3.3.1]nonanes (9-R-9BBN) and 1-halo-1-alkenes under carbon monoxide atmosphere is described.
Abstract: The synthesis of α,β-unsaturated ketones by means of the palladium-catalyzed cross-coupling reaction between 9-alkyl-9-borabicyclo[3.3.1]nonanes (9-R-9-BBN) and 1-halo-1-alkenes under carbon monoxide atmosphere is described.
TL;DR: In this paper, the conversion of hex-5-enopyranosides into substituted cyclohexanones (Ferrier rearrangement) was found to proceed efficiently with a catalytic amount of various mercury(II) salts at room temperature in a neutral solvent system.
Abstract: Conversion of hex-5-enopyranosides into substituted cyclohexanones (Ferrier rearrangement) was found to proceed efficiently with a catalytic amount of various mercury(II) salts at room temperature in a neutral solvent system. Among the mercury(II) salts tested, mercury(II) trifluoroacetate showed the highest activity. Four optically active cyclohexenones were prepared from hex-5-enopyranosides utilizing this method.
TL;DR: In this article, the potential energy surfaces of electronically excited states of SO2 have been investigated with ab initio molecular orbital method: Especially, the two-dimensional potential energy surface for the \ ildeC1B2 (21A′) state as a function of both the bond angle and bond distance has been carefully analyzed, including the spin-orbit interaction.
Abstract: The potential energy surfaces of electronically excited states of SO2 have been investigated with ab initio molecular orbital method: Especially, the two-dimensional potential energy surface for the \ ildeC1B2 (21A′) state as a function of both the bond angle and bond distance has been carefully analyzed, including the spin-orbit interaction. Energetically, 23A′ (13A1 in C2v) was found to be the most grobable state which concerns the reaction mechanism for the photodissociation pathway from the \ ildeC state (SO2 (\ ildeC1B2)→SO(3∑−)+O(3P)); however, other pathway may also be possible to go over the avoided crossing on a singlet potential surface.